Ignoring all legalities which may or may not apply in certain areas...
An aftermarket LED bulb will not fit a D2S light fitting. They will fit a halogen unit, but you may have to leave the read cover off (bad move), due to the size of the bulb drivers. Most current generation LEDs don't have active fans, but all previous generation do. All benefit from airflow, which is why as an aftermarket fitment, they aren't ideal.
Ignoring the marketing BS, its been tested time and time again that at about 25m, quality HIDs have the highest light output compared to (aftermarket) LED and halogen, but beaten by laser as fitted to the latest high end cars (and not to be confused with Osrams "laser" range which is their marketing for their brighter HIDs).
The Omega HIDs are not too bad TBH, but need clean lenses, clean projector unit (which gets dusty if driven without the rubber cover on the back), and newish, quality bulbs, such as Osram and a temp of about 4.2-4.5k. Halogen bulbs also degrade, so if the main beam is poor, put in new, quality halogen bulbs.
Obviously, show lights, like the whiter halogens, or the 6k and higher HIDs actually reduce illumination, so if you are after a certain look, there will always be a compromise between looks and function.
A bi-xenon conversion for an Omega would be a good compromise, but would be a tricky job.